3D Assembly of CoAl2O4 Spinel Nanosheets for Energy Storage

Two-dimensional (2D) materials have attracted attention for electrochemical energy storage applications because of their unique physical and chemical properties. However, the facile synthesis of thin 2D sheets remains a challenge. Herein, we demonstrate the formation of 3D assembly of thin Co-Al spinel sheets and carbon composite through a facile two steps process: followed by heating of this LDH at high temperature to form CoAl2O4/C. This composite with a high specific surface area (SSA) of 102.7 m2 g-1 showed enhanced energy storage application. The CoAl2O4/C is capable of delivering specific capacitance of 1394 F g-1 under 1 A g-1 current density with 87% capacitance retention after 5000 cycles. For asymmetric supercapacitor (ASC), the CoAl2O4/C and activated carbon (AC) were used as cathode and anode, respectively. The device CoAl2O4/C//AC exhibits a high energy density of 76.34 W h kg-1 at a power density of 750.045 W kg-1 with good cyclic durability of 79% after 10 000 cycles. The improved electrochemical activity may be due to the 3D assembly of thin 2D Co-Al spinel nanosheets that allows easy electron and mass transport, high surface area, synergistic interaction among different components, etc. for which Co-Al spinel/C composite will find application in energy storage.

Automated summary

In this study, a facile two-step process was used to form a 3D assembly of thin Co-Al spinel sheets and carbon composite, which exhibited high specific surface area and enhanced electrochemical activity. This composite showed potential for energy storage applications.